Older Jack Russell becoming aggresive

by Amy
(Ohio)

My mom has a Jack Russell terrier. I'm not sure how old he is he was adopted from the pound and he was already grown and that was around 9-10 years ago. He's always been a wonderful little guy, loving, well behaved, excellent with children of all ages. He has had his acting out moments like any other dog such as peeing on the floor or snapping at Mom but not trying to bite or be mean. It's very rare and as soon as he's done those things he gets his little "I'm sorry face" and comes over to love on you. He has also had occasional "episodes" where he has small seizures. He'll get very stiff and his eyes get glassy and water like he's crying. He never gets mean when these happen either, we sit with him and talk softly to him until he's over it and then he'll lay his head on our lap for a bit and get petted. These don't happen often either.

Recently he's had a few times where he's become aggressive. My mom lives with my sister and her family in the basement which is an apartment.. While mom's at work my sister and my teenage nieces .visit with Maxwell and take care of him. Well there's been 3 times in the last couple weeks that Maxwell growled at my sister and one of my nieces. It started when the landlady came with her nephew to look at a couple things to fix be fixed. My sister tried to let Maxwell outside because he doesn't like strangers (although he's never been mean to anyone) he growled at Sara but then was fine and she just sat with him while they looked at Mom's apartment and Max did fine the whole time. Another day my niece came down to visit with Maxwell like she does every day and Maxwell growled at her and there was one more time that he growled at my sister when she came down. This morning when mom got up she went to let Maxwell out like she does every morning and he not only growled at her but snapped at her. It wasn't a usual type of leave me alone snap either it was a very angry one and enough to make my mom scared. But then a few minutes later he was playing around and wanting petted like always.

We've called the vet and they said that it sounds like "typical Jack Russell behavior" but he's not acted like this before in the entire time that Mom;s had him. I was wondering if as they get older do they become more aggressive or is there something wrong with him and we need to find a different vet to talk to?